| 摘要 |
PURPOSE:To produce a magnetic carrier, capable of providing an optimum image according to the kind of a copier and having a wide resistance change ratio, by changing oxygen partial pressure in a firing atmosphere and producing magnetic carrier particles of a ferrite. CONSTITUTION:Magnetic carrier particles of a ferrite having a composition represented by the formula expressed in terms of bivalent or trivalent metallic oxides are produced by firing. In the process, the oxygen partial pressure in a firing atmosphere is changed so as to provide a desired value of particle resistance. Thereby a copied toner image attains a desired image quality. In the above-mentioned formula, M is any of Ni, Ni+Mn, Ni+Mg, Ni+Zn, Ni+ Mg+Mn, Ni+Zn+Mg+Mn, Ni+Mg+Mn+Cu and Ni+Zn+Mg+Mn+Cu, provided that the atomic ratio of Ni in M is >=0.05. A magnetic carrier having a wide resistance change ratio amounting to 10<6>-10<10> can be obtained by changing the firing atmosphere for production as described above. Because of this, the aimed carrier capable of providing an optimum image according to the machine type of a copier can be readily obtained. Furthermore, an optional image quality can be selected. |
